How are graphs plotted on a data set?

Question

Algorithms

How to build correct graphs for a data set? For example, remove too small and too large values, and build on the rest. What other options for screening data, where you can read about different options, about approximation.

Answer 1

I usually do this. Let's assume that the desired shape of the graph is known - a straight line, a parabola, a sinusoid, a surface of the second order ... I am looking for the coefficients of the best approximation using the least squares method. I look for each point the value of the residual error, I consider the average square of errors (sigma). I discard all points for which the error is greater than 2.5 * sigma, for the rest I look for the graph again. And so on, until the process stabilizes.
In general, it is necessary to write in more detail what kind of data, where they came from, in what range, what is needed from the graph - for example, should it strictly pass through the points, or should it pass in the area of ​​\u200b\u200bthe greatest condensation, is anything known about the dependence in advance. .. And so the task is too general.

Answer 2

Use Gnuplot, Luke.